TB May Have Reduced Leprosy
For most of the Middle Ages, leprosy was the scourge of Europe, its victims stigmatized and forced to huddle in caves or gather in charity camps run by monks. By 1300, University College of London physician and archaeologist Mark Spigelman says, "almost every town had a leprosarium."
But then, inexplicably, leprosy began to decline. Today, although it still exists and occasionally kills in some countries, leprosy is a treatable disease whose horrible heritage has dimmed with time.
A new survey confirms earlier findings that commercial fishing has wiped out 90 percent of large predatory fish in the past 50 years.
(Rodney Fox Expeditions Via Reuters)
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In research published last week in Royal Society Proceedings B, a team led by Spigelman and University College colleague Helen Donoghue suggested that leprosy's demise may have been caused by the rampant spread of tuberculosis.
"TB is a much more aggressive, faster disease," Spigelman said in a telephone interview. "And it's a disease of crowds."
Spigelman said the team became aware of a possible relationship when bone tissue of a shrouded mummy from a 1st-century tomb in Israel showed evidence of infection by both TB and leprosy.
The team then examined human remains from Europe between 100 and 1500 A.D. and found both diseases in 42 percent of them, Spigelman said. "Leprosy doesn't kill you, but you're isolated, and you suffer from diet and immune system problems. TB is quite likely to be the thing that comes in and kills" -- especially as Europe's population density began to increase.
That created fertile ground for the spread of TB, Spigelman said. Lepers, already weakened, were particularly susceptible and died before spreading leprosy to others.
"As the incidence of TB went up, leprosy went down," he said. "It's almost a one-for-one relationship."
-- Guy Gugliotta
As Trees Fall, So Does Diversity
When tropical rain forests are cut down, the forest that grows back is a pale version of the original -- at least on the genetic level.
That's the conclusion of ecologists at the University of Connecticut who analyzed the relationship between old-growth and second-growth forests in Costa Rica.
Old-growth forest contains fully mature trees that have not been significantly disturbed by human beings over the trees' lifetimes. Second growth is what appears when cleared land is invaded by woody plants and goes through the predictable stages of development called ecological succession.
Uzay U. Sezen and colleagues analyzed the genetic diversity of trees of the canopy palm species Iriartea deltoidea in a patch of forest last cut in 1981. Next to it was old-growth forest that was its only source of seed and pollen.
The researchers compared genes in the 130 second-growth palms with the genes in the old-growth trees. They found that among 66 old-growth trees, two contributed 56 percent of the genes in the second-growth stand, which contained 130 trees. Twenty-three of the old-growth trees contributed the rest of the genes, and 41 trees had no progeny.
"More than half the founding Iriartea population were full or half-siblings," the authors wrote in the journal Science. Why two of the old-growth trees were such dominant contributors isn't known.
The researchers concluded that it will take many generations for second-growth forests to achieve anything like the genetic diversity of old growth that preceded them.
-- David Brown
New Signs of Decline in Big Fish
A new survey of the world's oceans has confirmed the startling finding, first reported two years ago, that commercial fishing has wiped out 90 percent of large predatory fish in the past 50 years, researchers report in the current issue of Royal Society Proceedings B in Britain.
The new survey -- funded by the Pew Institute for Ocean Science and the Census of Marine Life -- encompasses twice as many studies and examines ecosystems that had not previously been assessed, such as the equatorial Pacific and several coral reefs.
Ransom A. Myers, a professor at Dalhousie University in Nova Scotia who authored both surveys, said the plight of predatory fish is "if anything worse" than the earlier data indicated.
"Industrial fisheries have changed marine ecosystems in fundamental ways," Myers wrote. "Current fishing mortalities projected into the future could lead to the extinction of certain sensitive species of sharks and other large predators at the top of the food web."
In their new paper, Myers and Boris Worm, another Dalhousie University professor, conclude that "today's management decisions will determine whether we will enjoy biologically diverse, economically profitable fish communities 20 or 50 years from now, or whether we will have to look back on a history of collapse and extinction that was not reversed in time."
-- Juliet Eilperin
